Method of transmitting broadcast signal, method of processing broadcast signal and apparatus for the same

ABSTRACT

A method of processing a broadcast signal relevant to an emergency alert and a broadcast receiver for the same are disclosed, by which information on a channel for carrying an emergency alert broadcast can be prevented from being overlapped with information on other general channels. The present disclosure generating an emergency alert table including frequency information of an emergency alert channel, and transmitting a digital broadcasting signal including the emergency alert table, wherein the frequency information of the emergency alert channel is inserted in a descriptor that provides an additional pointer to the emergency alert channel, wherein the descriptor references the emergency alert channel by means of the frequency information.

This application claims the benefit of the Korean Patent Application No.10-2006-0115624, filed on Nov. 22, 2006, which is hereby incorporated byreference as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Disclosure

The present disclosure relates to a method of transmitting broadcastsignal, apparatus for processing broadcast signal and method thereof.

2. Discussion of the Related Art

Recently, natural disasters including unexpected earthquakes and floodsor emergency situations including terrors, arsons and the like tend totake place more frequently. Natural disasters due to environmentalpollution or terrors cause more damages widely and their secondaryeffects become more powerful. In case that one of the aforesaidemergency takes place, the coverage of the emergency is filed. Newsrelating to the emergency is then broadcasted in a format such as anewsflash and the like on all channels after a prescribed duration.

Basic protocol for processing an emergency alert system message has beendetermined for televisions and the like for sale in North America. And,a basic protocol for receiving and processing an emergency alert systemmessage correctly is determined for cable digital TVs as well. However,in case that the emergency alert system message defined in thespecifications of cable digital TV, e.g., an emergency alert table(hereinafter abbreviated EAT) is intactly applied to a terrestrialbroadcasting system, the following problems rise.

First of all, in case of applying an EAT defined for a related art cabledigital broadcasting environment to a terrestrial broadcasting system,information on a channel for carrying emergency alert broadcast may beduplicated instead of being unified. For instance, in case of a cablebroadcasting system in which a single broadcasting station is capable ofmanaging all channels, channel numbers of all channels broadcastedin-band can be managed using a major channel number (physical channelnumber) and a minor channel number (program number) only. Yet, in caseof terrestrial broadcasting, there exist a plurality of terrestrialbroadcasting stations separately. So, a channel number of a channelbroadcasted by each of the broadcasting stations can be arbitrarily set.So, the identical major and minor channel numbers may be used bydifferent broadcasting stations.

Secondly, in case of applying the EAT defined in the related art cabledigital broadcasting environment to a terrestrial broadcasting system, arelay service provider is able to change a frequency of a channel forcarrying emergency alert broadcast arbitrarily in retransmitting theEAT. So, although an emergency takes place, a receiver may besubstantially tuned to a channel differing from the initially intendedchannel for carrying the emergency alert broadcast.

SUMMARY OF THE INVENTION

Accordingly, the present disclosure is directed to a method oftransmitting broadcast signal, an apparatus for processing broadcastsignal and method thereof that substantially obviate one or moreproblems due to limitations and disadvantages of the related art.

An object of the present disclosure is to provide a method oftransmitting broadcast signal relevant to an emergency alert, method ofprocessing broadcast signal and a broadcast receiver for the same, bywhich information on a channel for carrying an emergency alert broadcastcan be prevented from being overlapped with information on other generalchannels.

Additional advantages, objects, and features of the disclosure will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of thedisclosure. The objectives and other advantages of the disclosure may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the disclosure, as embodied and broadly described herein, amethod of transmitting a digital broadcast signal according to thepresent disclosure comprises the steps of generating an emergency alerttable including frequency information of an emergency alert channel, andtransmitting a digital broadcasting signal including the emergency alerttable, wherein the frequency information of the emergency alert channelis inserted in a descriptor that provides an additional pointer to theemergency alert channel, wherein the descriptor references the emergencyalert channel by means of the frequency information.

In another aspect of the present disclosure, a method of transmitting adigital broadcast signal according to the present disclosure comprisesthe steps of generating an emergency alert table including programnumber information of an emergency alert channel, and transmitting adigital broadcasting signal including the emergency alert table, whereinthe program number information of the emergency alert channel isinserted in a descriptor that provides an additional pointer to theemergency alert channel, wherein the descriptor references the emergencyalert channel by means of the program number information.

In another aspect of the present disclosure, a method of processingemergency alert information in a receiver comprises the steps ofreceiving a digital broadcasting signal including frequency informationof an emergency alert channel in emergency alert table, parsing theemergency alert table and extracting the frequency information andchannel number information of the emergency alert channel from theemergency alert table, and tuning to the emergency alert channel when astate of emergency channel tuning to the emergency alert channel occurs,wherein the emergency alert channel is acquired from the channel numberinformation and additionally referenced by the frequency information.

In another aspect of the present disclosure, a method of processingemergency alert information in a receiver comprises the steps ofreceiving a digital broadcasting signal including program numberinformation of an emergency alert channel in the emergency alert table,parsing the emergency alert table and extracting the program numberinformation and channel number information of the emergency alertchannel from the emergency alert table, and tuning to the emergencyalert channel if a state of emergency channel tuning to the emergencyalert channel occurs, wherein the emergency alert channel is acquiredfrom the channel number and additionally referenced by the programnumber information.

In another aspect of the present disclosure, a digital televisionreceiver comprises a tuner for receiving a digital broadcasting signalincluding frequency information of an emergency alert channel in theemergency alert table, a parser for parsing the emergency alert tableand extracting the frequency information and channel number informationof the emergency alert channel from the emergency alert table, and acontroller for controlling the tuner to tune to the emergency alertchannel when a state of emergency channel tuning to the emergency alertchannel occurs, wherein the emergency alert channel is acquired from thechannel number information and additionally referenced by the frequencyinformation.

In another aspect of the present disclosure, a digital televisionreceiver comprises a tuner for receiving a digital broadcasting signalincluding program number information of an emergency alert channel inthe emergency alert table, a parser for parsing the emergency alerttable and extracting the program number information and channel numberinformation of the emergency alert channel from the emergency alerttable, and a controller for controlling the tuner to tune to theemergency alert channel when a state of emergency channel tuning to theemergency alert channel occurs, wherein the emergency alert channel isacquired from the channel number information and additionally referencedby the program number information.

It is to be understood that both the foregoing general description andthe following detailed description of the present disclosure areexemplary and explanatory and are intended to provide furtherexplanation of the disclosure as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the disclosure andtogether with the description serve to explain the principle of thedisclosure. In the drawings:

FIG. 1 is a diagram of a bit stream syntax of an emergency alert table(EAT) defined by terrestrial broadcasting according to a firstembodiment of the present disclosure;

FIG. 2 is a diagram of an EAT channel descriptor(EAT_channel_descriptor) defined by terrestrial broadcasting accordingto a first embodiment of the present disclosure;

FIG. 3 is a diagram of a system, in which a relay service providertransmits EAT using a predetermined protocol, according to oneembodiment of the present disclosure;

FIG. 4 is a diagram of a bit stream syntax of an emergency alert table(EAT) defined by terrestrial broadcasting according to a secondembodiment of the present disclosure;

FIG. 5 is a diagram of an EAT channel descriptor(EAT_channel_descriptor) defined by terrestrial broadcasting accordingto a second embodiment of the present disclosure;

FIG. 6 is a block diagram of a broadcast receiver for receiving andprocessing EAT according to one embodiment of the present disclosure;and

FIG. 7 is a flowchart of a process for receiving and processing EATaccording to one embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the embodiments of the presentdisclosure, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

An emergency alert system message can be received via OOB (out of band)by inserting a cable card (CableCARD) in a cable digital TV of NorthAmerica. If the cable card is not inserted, the emergency alert systemmessage can be received via in-band. It is checked whether the receivedemergency alert system (EAS) message is received via a band differentfrom that for a previously received emergency alert system message. Ifthe received emergency alert system message is received via the banddifferent from that of the previously received emergency alert systemmessage, it is able to omit a redundancy check of the emergency alertsystem message by clearing a sequence number. On the other hand, if thereceived emergency alert system message is received via the same band ofthe previously received emergency alert system message, the redundancycheck of the emergency alert system message is carried out. If it is aredundant message, the processing of the emergency alert system messageis stopped.

After completion of the basic check, a channel should be switched to anemergency alert system channel, on which emergency alert system contentsare being broadcasted, according to a priority of the correspondingemergency alert system message. A number of the channel can bediscriminated into an in-band EAS or an OOB EAS according to a receptionband of the emergency alert system message.

The emergency alert system message received via in-band can betransmitted by including an emergency alert system broadcast with a pairof a major channel number and a minor channel number. This scheme ispossible because there is a cable broadcasting station as a subject thatmanages all broadcast channel numbers under North America CableBroadcasting System. Yet, in case that the above-explained specificationof cable digital broadcasting are applied to a terrestrial broadcastingsystem as they are, the following problem may rise.

First of all, terrestrial broadcasts received by aterrestrial-receivable digital TV include signals transmitted bydifferent terrestrial broadcasting stations, respectively. A channelnumber of a channel transmitted by each of the different terrestrialbroadcasting stations can be randomly set up according to PSIP (programand system information protocol) standards. Assuming that differentbroadcasting stations simultaneously use a channel number of a channelon which an emergency alert situation is being broadcasted, a digital TVhaving received an emergency alert system message (e.g., EAT) has aproblem in deciding a channel to switch. Due to such a problem, it isunable to apply syntax of an emergency alert system message employed byNorth American cable digital TV to a terrestrial broadcasting system asit is.

Hence, the present disclosure intends to modify and expand a syntax ofEAT to apply specifications of an emergency alert system message used bya cable digital broadcasting system to a terrestrial broadcastingsystem. Meanwhile, in order to apply emergency alert broadcast statementidentically by considering a broadcasting environment when a terrestrialbroadcast is retransmitted via a relay service provider, the presentdisclosure is also characterized in designing EAT the relay serviceprovider need not amend.

As mentioned in the foregoing description, since all broadcasts in theNorth American Cable Broadcasting System are managed by cablebroadcasting stations, it is able to set broadcast titles or channelnumbers arbitrarily. In normal cases, the broadcast titles or channelnumbers can be set different from each other. When a cable broadcastingstation transmits an emergency alert system message via in-band, if apriority of the emergency alert system message is high enough to switchto a channel on which an emergency alert situation is being broadcasted,it facilitated to switch to an emergency alert system broadcast channelby performing channel tuning to a channel corresponding to a channelnumber received by being included in the message according to SCTE(society of cable television engineers) 18, and more particularly, toemergency alert message for cable.

The above-described emergency alert broadcast channel processing methodin the conventional North American cable broadcasting system can beprocessed without special problems since there exits the assumption ofprotocol indicating that all channel numbers of the receive cable arenot overlapped with each other. Yet, if the emergency alert messagesyntax of the able broadcasting, which is defined by SCTE 18, is appliedto a terrestrial broadcasting system as it is, a problem may be causedby the problem of channel overlapping possibility. Hence, the presentdisclosure intends to solve the problem of the overlapped channeloccurrence, the problem that the relay service provider should amendEAT, and the like in a manner of compensating/expanding syntax of anemergency alert broadcast message used for a cable broadcasting system.

FIG. 1 is a diagram of a bit stream syntax of an emergency alert table(EAT) defined by terrestrial broadcasting according to a firstembodiment of the present disclosure, and FIG. 2 is a diagram of an EATchannel descriptor (EAT_channel_descriptor) defined by terrestrialbroadcasting according to a first embodiment of the present disclosure.

EAT (emergency alert table) and EAT channel descriptor(EAT_channel_descriptor), which are defined by the present disclosure,are explained with reference to FIG. 1 and FIG. 2 as follows.

First of all, an emergency alert broadcast message specification ofcable broadcasting is defined to enable both of an emergency alertmessage received via in-band and an emergency alert message received viaOOB (out off band) to be processed. Yet, in terrestrial broadcasting, itis unable to receive an emergency alert message via OOB. Hence, thepresent disclosure is characterized in defining EAT of a terrestrialbroadcasting system, a shown in FIG. 1, in a manner of removing allfields associated with OOB from EAT of a cable broadcasting system. Ifso, a processing speed for EAT of a terrestrial broadcast can beimproved by deleting the unnecessary fields.

Fields shown in FIG. 1 are described in brief as follows. Of course,they can be understood more easily with reference to EAT of cablebroadcasting in some cases.

Referring to FIG. 1, a ‘table_ID’ field is a syntax for indicating anemergency alert message of a terrestrial broadcast. For instance, the‘table_ID’ field can be set to 0xD8. “section_syntax_indicator” fieldcan be set to 1. This 1-bit field shall be set to ‘1’. It denotes thatthe table section follows the generic MPEG-2 section syntax beyond thesection_length field. The ‘section_length’ field defines the number ofremaining bytes and shall be set to a value smaller than 4,093. This12-bit field specifying the number of remaining bytes in this sectionimmediately follows the section_length field up to the end of thesection. The value of the section_length shall be no larger than 4093.

And, ‘sequence_number’ field can indicate a sequence of emergency alertmessage. If a semantic of the message is changed, this field can beincremented by a value 0 to 31. (This 5-bit field is the sequence numberof this emergency alert message. The sequence_number shall beincremented by 1 (modulo 32), when any change occurs in the informationcarried in the emergency alert message). And, this field can indicate aversion of the emergency alert message. “current_next_indicator” field,which is 1-bit indicator, shall always be set to ‘1’ to indicate thatthe table sent is always currently applicable.

“section number” field indicates that a table sent shall occupy a lengthof at least one section and can be set to 0x00 (this table shall be atmost one section long). “protocol_version” field indicates a versionvalue of PSIP (Program and System Information Protocol). This 8-bitunsigned integer field whose function is to allow, in the future, thistable type to carry parameters that may be structured differently thanthose defined in the current protocol. “EAS_originator_code” field canindicate the entity that originally initiated the activation of the EAS.“EAS_event_code_length” field can indicate the length in bytes of theEAS_event_code field to follow. “EAS_event_code” field can indicate thenature of the EAS activation. For instance, this field can indicate sucha type of emergency as flood, earthquake, terror, etc. together withemergency information such as large-scale earthquake, medium-scaleearthquake, small-scale earthquake, etc.

“nature_of_activation_text_length” field can indicate the total lengthin bytes of the nature_of_activation_text( ) field to follow. Forinstance, if a value of “nature_of_activation_text_length” field is ‘0’,“nature_of_activation_text” can indicate that thenature_of_activation_text( ) field is not included in this alertmessage. “nature_of_activation_text” field may contain a syntax whichrepresents a short textual representation of the event code foron-screen display.

“alert_message_time_remaining” field, which is an 8-bit unsigned integerfield, in the range 0 to 120, shall indicate the time remaining in thealert message, in seconds. A value of zero shall indicate an alertmessage period of indefinite duration. And, the“alert_message_time_remaining” field can indicate a duration time, whichshould be sustained until an emergency alert message turn into aninterrupt message returns, by a second unit. “event_start_time” field,which is a 32-bit unsigned integer quantity, represents the start timeof this alert event as the number of seconds since 00 hours UTC3, Jan.6, 1980. Meanwhile, according to a time comparison to an STT time of acorresponding channel with reference to GPS time, in case of a pasttime, a terrestrial broadcast receiver ignores the EAT. In case of afuture time, it can decided whether to load the EAT in a memory of theterrestrial broadcast receiver by comparison to a value of“event_duration”. And, the “event_duration” field can be set to a 16-bitunsigned integer that, when nonzero, represents the number of minutesthe alert is expected to last. A value of zero indicates that the eventduration is unknown (indefinite). And, the terrestrial broadcastreceiver can delete the no-longer useful previous emergency alert eventstored in the memory of the terrestrial broadcast receiver using“event_start_time” and “event_duration” fields.

“alert_priority” field can mean a syntax indicating a priority orsignificance of an emergency. “alert_text_length” field indicates thenumber of total bytes of “alert_text( )” field and, for instance, canbeset to a 16-bit unsigned integer number that shall define the totallength in bytes of the alert_text( ) field to follow. A value of zeroindicates the alert_text( ) field is not included in this alert message.And, the “alert_text( )” field may have a data structure containing amultiple_string_structure( ) which shall represent a textual descriptionof the emergency alert for on-screen display. And, the emergency alerttext can be set to be slowly scrolled bottom to top or right to left ona screen of the terrestrial broadcast receiver.

“location_code_count” field can be set to an 8-bit unsigned integernumber in the range 1 to 31 that shall represent the number of regiondefinitions to follow in the “for” loop. Yet, in the region definitions,the regional names according to administrative district discriminationin U.S.A. are exemplarily used, which does not restrict the scope of theappended claims and heir equivalents of the present disclosure.“state_code” field can be set to an 8-bit unsigned number in the range 0to 99 that represents the State, Territory or Offshore (Marine Area)affected by the emergency alert. The “state_code” field shall be codedaccording to State and Territory FIPS number codes. The value of 0 shallindicate all states, or a national level alert. “state_subdivision_code”field can be set to an 8-bit numbering the range 0 to 99. And,“county_code” field represents a specific county of the state relevantto an emergency and can be set to a number in the range 0 to 99. The“county_code” field can be coded according to FIPS number codes of astate and area. If the field is set to 0, it can indicate that allcounties are in emergency.

“exception_major_channel_number” field is able to represent a majorchannel number of an exception service in association with in-band SI.And, “exception_minor_channel_number” field can represent a minorchannel number of an exception service in association with in-band SI ifit is not set to 0.

In the present disclosure, new fields required for channel tuning aredefined in the descriptor part shown in FIG. 1 to solve the overlappingproblem of channel number. An EAT channel descriptor(EAT_channel_descriptor) proposed by the present disclosure is shown inFIG. 2. The name of the EAT channel descriptor is just exemplary. TheEAT channel descriptor is explained in detail as follows.

“descriptor_tag” field is an field that identifies whether acorresponding descriptor is an EAT channel descriptor and can be set to‘0xEA’ for example. “descriptor_length” field can be used to represent alength or size of a corresponding descriptor.“details_major_channel_number” field represents a major channel numberfor broadcasting an emergency alert broadcast. And,“details_minor_channel_number” field represents a minor channel numberfor broadcasting an emergency alert broadcast.

“carrier_frequency” field identifies a frequency for transmitting anemergency alert broadcast and “details_channel_programNumber” fieldidentifies a program number within the frequency for transmitting theemergency alert broadcast. And, “details_channel_tsID” field can be usedas a field that identifies a transport stream ID for transmittingbroadcast contents.

The present disclosure defines the channel number information ofterrestrial broadcasting for transmitting an emergency alert broadcastin an EAT channel descriptor (EAT_channel_descriptor) to enable eachterrestrial broadcasting station to be discriminated in accordance witha preset reference. The channel number information may be defined in abody part of the EAT table. The channel number information can bedetermined via the “details_major_channel_number” and“details_minor_channel_number” fields.

Meanwhile, the present disclosure defines frequency information ofterrestrial broadcasting for transmitting an emergency alert broadcastin an EAT channel descriptor to enable each terrestrial broadcastingstation to be discriminated in accordance with a preset reference. Thechannel number information can be referenced by the “carrier_frequency”field. Thus, in case that the EAT channel descriptor(EAT_channel_descriptor) shown in FIG. 2 is added to an EAT of aterrestrial broadcast signal, it is able to remove the program numberoverlapping within a frequency. Hence, it is able to define a channel,which carries an emergency alert broadcast without the channeloverlapping occurrence, in EAT.

FIG. 3 is a diagram of a system, in which a relay service providertransmits EAT using a predetermined protocol, according to oneembodiment of the present disclosure. A method of transmitting an EAT,if a relay service provider retransmits a terrestrial broadcast, isexplained with reference to FIG. 3 as follows.

First of all, in case that a terrestrial broadcast is retransmitted viaa relay service provider, a frequency of a corresponding terrestrialchannel can be changed. So, it is highly probable that the emergencyalert message format (e.g., EAT channel descriptorEAT_channel_descriptor) of the terrestrial broadcasting system definedin FIG. 1 and FIG. 2 may not perform channel switching to a correctchannel. This is because the terrestrial relay service provider, asshown in FIG. 3, may perform retransmission by mixing cable channel,satellite channel, terrestrial channel and the like together withoutusing a terrestrial frequency transmitted by a terrestrial broadcastingstation. In this case, it is highly probable that the frequencytransmitted by the terrestrial broadcasting station may not be used dueto the problem of the overlapping with another channel.

FIG. 4 is a diagram of a bit stream syntax of an emergency alert table(EAT) defined by terrestrial broadcasting according to a secondembodiment of the present disclosure, and FIG. 5 is a diagram of an EATchannel descriptor (EAT_channel_descriptor) defined by terrestrialbroadcasting according to a second embodiment of the present disclosure.Newly defined EAT (emergency alert table) and EAT channel descriptor(EAT_channel_descriptor) of terrestrial broadcasting according to thepresent disclosure are explained as follows.

Compared to the first embodiment of the present disclosure shown in FIG.1 and FIG. 2, the second embodiment of the present disclosure ischaracterized in adding a channel index field (channel_index). A channelindex field shown in FIG. 4 or FIG. 5 is usable in representinginformation that identifies a relay service provider who manages atleast one location. The channel index field is designed in a manner ofbeing defined below a location code count field (location_code_count) inan EAT channel descriptor (EAT_channel_descriptor) to be mapped to eachother. In particular, to prepare for a case that a terrestrial channelis retransmitted via a relay service provider, the present disclosuredefines an index (channel_index) of a transmission location using alocation code (location_code_count) in a format (EAT) of an emergencyalert message.

Since a corresponding frequency and a channel index of an emergencyalert broadcast of a corresponding location are defined in the EATchannel descriptor (EAT_channel_descriptor), although the relay serviceprovider does not attempt to change the EAT or read the descriptor, areceiver can be normally tuned to an emergency alert broadcast channelin case of an emergency occurrence. Yet, it is mandatory for the presentdisclosure to amend the ‘location_code_count’ field by considering aterrestrial retransmission procedure, whereas ‘location_code_count’field is optional in EAT used for an emergency alert broadcast of NorthAmerican Cable Broadcasting.

Details are explained in the following description for example. First ofall, it is assumed that a terrestrial broadcasting station ‘MBC’transmits broadcast signals including EAT and the like to a broadcastrelay service provider ‘Taejeon’, a broadcast relay service provider‘Chungju’, a broadcast relay service provider ‘Yeouido’, and the like.In this case, a channel index of the broadcast relay service provider‘Taejeon’ is set to 0, a channel index of the broadcast relay serviceprovider ‘Chungju’ is set to 1, and a channel index of the broadcastrelay service provider ‘Yeouido’ is set to 2. If the channel index is 0,a physical channel number of the MBC broadcasting is mapped to ‘60’. Ifthe channel index is 1, a physical channel number of the MBCbroadcasting is mapped to ‘70’. If the channel index is 2, a physicalchannel number of the MBC broadcasting is mapped to ‘80’.

Hence, even if a relay service provider having received the EAT and thelike transmits the received EAT to a broadcast receiver intactly withoutamending a physical channel number, a frequency and the like separatelyor without changing an EAT channel descriptor and the like, thebroadcast receiver can be tuned to an initially scheduled emergencyalert broadcast channel without error.

FIG. 6 is a block diagram of a broadcast receiver for receiving andprocessing EAT according to one embodiment of the present disclosure. Anoperation of a broadcast receiver, which receives and processes an EATchannel descriptor, according to the present disclosure is explainedwith reference to FIG. 6 as follows. Referring to FIG. 6, a broadcastreceiver 601 according to the present disclosure includes a tuner 602, ademodulator 603, a demultiplexer 604, an A/V decoder 605, a display unit606, a PSI/PSIP database 607, a PSI/PSIP decoder 608, a channel manager609, a channel map 610, an application and UI manager 611, a flashmemory 601, and the like. In this case, the broadcast receiver 601 meansa digital television (DTV) capable of terrestrial broadcast reception orthe like for example.

The tuner 602 is able to receive a terrestrial broadcast signalcontaining a PSI/PSIP (program and system information/program and systeminformation protocol) table. For instance, the PSIP table can include anemergency alert table (EAT) and the like. And, operations of the tuner602 can be controlled by the channel manager 609. Moreover, the tuner602 enables a result from receiving the terrestrial broadcast signal tobe recorded back in the channel manager 609. The demodulator 603demodulates a signal tuned by the tuner 602 by VSB/EVSB (vestigialsideband/enhanced vestigial sideband) demodulation.

The demultiplexer 604 plays a role in demultiplexing audio data, videodata, and PSI/PSIP table data from the signal demodulated by thedemodulator 603. In this case, the audio/video data demultiplexing canbe controlled by the channel manager 609, whereas the PSI/PSIP tabledata demultiplexing can be controlled by the PSI/PSIP decoder 608. Thedemultiplexed PSI/PSIP table is transferred to the PSI/PSIP decoder 608,while the demultiplexed audio/video data are transferred to the A/Vdecoder 605. The A/V decoder 605 then decodes the transferred data.

The PSI/PSIP decoder 608 parses a PSI/PSIP section, reads the entirerest of actual section data failing to be section-filtered by thedemultiplexer 604, and then records the data in the PSI/PSIP database607. And, the PSI/PSIP decoder 608 is capable of parsing EAT informationcontained in the PSI/PSIP. Using channel information and the likecontained in the parsed EAT information, the channel manager 609controls the tuner 602 to be tuned to a channel of a terrestrialbroadcast that carries an emergency alert broadcast.

Meanwhile, the EAT can include the EAT channel descriptor(EAT_channel_descriptor) shown in FIG. 2 and FIG. 5, which has beensufficiently explained in the descriptions of FIG. 2 and FIG. 5. And, itis apparent to those skilled in the art that a DTV for processing theEAT can be designed through FIG. 2 and FIG. 5.

FIG. 7 is a flowchart of a process for receiving and processing EATaccording to one embodiment of the present disclosure. An EAT processingmethod according to the present disclosure is explained with referenceto FIG. 7 as follows. In particular, FIG. 7 schematically depicts thedescriptions for FIGS. 1 to 6 in accordance with a time flow.

Referring to FIG. 7, a broadcast receiver receives an emergency alerttable (EAT) containing a channel index field (channel_index) thatidentifies a relay service provider managing at least one location(S701). The broadcast receiver may be a DTV or the like for example. Theabove-explained channel index can be added below a location code countfield (location_code_count) in an EAT channel descriptor of the EAT. Thereceiver reads out physical channel number information of a terrestrialbroadcasting station mapped by the channel index field (S702). In thiscase, the physical channel number information can be defined in‘details_major_channel_number’ and ‘details_minor_channel_number’ fieldsand the like below the EAT channel descriptor. And the physical channelnumber information can be additionally referenced by the frequencyinformation and/or the program number information.

In case that an emergency takes place, the receiver is tuned to aphysical channel number of the terrestrial broadcasting station (S703).Accordingly, since a channel number of a specific terrestrialbroadcasting station per location is determined in accordance with achannel index, despite that a relay service provider transmits areceived EAT intact to a broadcast receiver, the broadcast receiver hasno problem in being tuned to an emergency alert channel.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present disclosurewithout departing from the spirit or scope of the inventions. Thus, itis intended that the present disclosure covers the modifications andvariations of this disclosure provided they come within the scope of theappended claims and their equivalents.

1. A method of transmitting a digital broadcasting signal, comprising:generating an emergency alert table including a plurality of datafields, wherein one of the data fields includes information thatincludes an emergency alert table descriptor, wherein the emergencyalert table descriptor contains additional data fields, wherein one ofthe additional data fields indicates frequency information of anemergency alert channel; and transmitting, at a digital broadcasttransmitter, a digital broadcasting signal including the emergency alerttable; wherein the frequency information of the emergency alert channelis inserted in the additional data field that provides an additionalpointer to the emergency alert channel, wherein the emergency alerttable descriptor references the emergency alert channel by means of thefrequency information.
 2. The method of claim 1, wherein the emergencyalert table further includes channel number information that representsan virtual channel number of the emergency alert channel.
 3. The methodof claim 2, wherein the channel number information includes an in-bandmajor channel number and an in-band minor channel number of theemergency alert channel.
 4. The method of claim 1, wherein the emergencyalert table further includes alert priority information that indicatesthe priority of the alert.